Spark plug



Feb. 3. 1925. 1,524,687 a w. J. cfu-111.1.v

SPARKPLUG Filed March 12, 1920 l INVENTOR.

f -ATTORNY.

Patented Feb. 3, 1925.

UNITED STATES WILLIAM J. lCAHILL, OIF'SAYRE, PENNSYLVANIA.

SPARK PLUG.

Application filed March 12, 1920. Serial No. 365,239.

To all whom z't may concer/n.'

Be it known that I, WILLIAM J. CAHILL, a citizen of the United States of America, residing at 403 North Elmer Avenue, Sayre, in the county of Bradford and State of Pennsylvania, have invented certain new and useful Improvements in Spark Plugs, of which the following is a specification.

This invention relates to improvements in spark plugs for internal combustion engines and has for an object to provide an improved structure which will be air proof, having all connections completely housed in ab simple and etcient manner.

Another object of the improvement .is to have the insulating member carrying one of the terminals readily removable and adjustable relative to the other terminal without thenecessity of removing the casing of the plug from the engine.

Another object of the improvement is to have the terminal which connects the feed wire to one of the terminals arranged axially with the terminal and outer protective casing whereby the latter may be readily removed without the necessity of disco-nnecting the wire and terminal.

Figure 1, is a longitudinal section through the spark plug.

Figure 2, is a. horizontal transverse section on 1ine2'-2 of Figure l.

Figure 3, is a detail view of the central terminal and connections.

' 1, indicates a casing having external rthreads 2, at the lower end adapted tof-be screwed into the cylinder and support the contact terminal 3, properly within the cylinder. The casing 1s further provided with 4internal screw threads as at 4, at the outer end thereof and acentral bore 5, restricted at the lower end to form a shoulder lor seat 6. An insulating member 7, is fitted into the central bore of the casing being held in place by means of the protecting casing 8, screwed into Athe internal screw 12, carried thereby with respect to the lower contact terminal 3, in order that a proper air gap between the two contact terminals may be assured.

The protecting easing 8, is provided with a. threaded aperture .13, at the upper end thereofV to receive a knurled bushing 14, through which the feed wire 15, is passed. The contact terminal 12, is threaded at its upper -end and is adapted to receive a threaded sleeve 16, into the upper end of which is detachably secured by a set screw 17 the exposed end of the wire 15. This arrangement permits the wire and terminal being securely fastened together after which the protecting casing 8, is passed down over the connection screwed into the casing to hold the insulating member 'rml in place and form a water tight covering for the connections. The bushing 14, is then secured into place thereby closing the aperture in the protect.- ing casing.

The protecting ease can, of course, be made of an insulating material but pref erably consists of a metal body lined with an insulating material 18. With such a construction the easing may be readily removed without disturbing the connections between the center terminal and the feed wire, and if desirable the central terminal and insulating member may be readily, removed for cleaning without removing the entire plug from `the cylinder.

I claim,

A spark plug comprising an internally flanged casing, an insulating shell provided with a flanged collar adapted to seat in said flanged casing, a terminal carried by said insulating shell, a protective easing having threaded engagement with the upper end of saidA internally ianged casing adapted to surround and hold said insulated shell in position, said protective easing being provided with an aperture in the upper end thereof, an orifieed bushing removably reeeived in said aperture, and a feed wire passing therethrough and connected with the terminal carried in the insulating shell, said feed wire and terminal being in axial alignment, whereby the protective casing may be removed longitudinally for exposing said terminal connection and the removal of said insulating shell.

In testimony whereof I ailix m signature.

Y WlLLIAM J. AHILL 

